by direct observation, as
decreed by the "restorers" of anatomy. Embryonic development was,
however, also studied independently of other disciplines by a smaller
group of individuals, and the study of chick development by Aldrovandus,
Coiter, and Fabricius ab Aquapendente laid the basic groundwork of
descriptive embryology. In either case, during the last half of the
sixteenth century the attempt of the embryologist to break with the
traditions of the past was overt, although consistently unsuccessful.
When dealing with the fetus, the investigators of this period were,
almost to a man, Galenists influenced to varying degrees by Hippocrates,
Aristotle, and Avicenna. Each felt compelled to challenge the immediate
authority, and yet their intellectual isolation from the past was
incomplete, and their views on embryogeny corresponded with more often
than they differed from those of the person they railed against.

Embryology emerged as a distinct scientific discipline during the last
half of the sixteenth century and early years of the seventeenth century
as a result of the aforementioned investigations of Aldrovandus, Coiter,
and Fabricius. Concerned with description and depiction of the anatomy
of the embryo, they established a period of macro-iconography in
embryology. The macro-iconographic era was empirical and based upon
first-hand observation; it was concerned more with the facts than with
the theories of development. This empiricism existed in competition with
a declining, richly vitalistic Aristotelian rationalism which had
virtually eliminated empiricism during the scholastic period. However,
the decline of this vitalistic rationalism coincided with the rise of a
mechanistic rationalism which had its roots in ancient Greek atomistic
theories of matter. The empiricism comprising the _leitmotif_ of the
macro-iconographic movement then became blended with, or, more often,
submerged within, the new variety of rationalism; hence, mechanistic
rationalism, divorced entirely or virtually from empiricism,
characterizes embryology during the first half of the seventeenth
century. It is a particularly vigorous strain of seventeenth-century
English embryological thought, well illustrated in the writings of that
English man of affairs, Sir Kenelm Digby.

Digby, whose name, according to one biographer, "is almost synonymous
with genius and eccentricity,"[2] could claim our attention not only as
a scientist of talent, but also